Did you do this per gmail instructions?

I turned on 2-Step Verification and an app on my phone or computer stopped working When you turn on 2-Step Verification, any apps that need access to your Google Account will stop working until you enter an App Password in place of your normal password.

Common applications and devices that require an App Password include:

Old versions of email clients such as Outlook, Apple Mail and Thunderbird The email app that comes with your phone (but is not made by Google) Some chat, contacts and YouTube clients Note: If you're running the latest operating system on your iPhone/iPad or Mac computer, you will no longer have to use App passwords to use 2-Step Verification.

You do not need to memorize App Passwords because every App Password is only used once. You can generate a new App Password whenever you’re asked for one--even for a device or application you’ve authorized before.

This post is about using T-Bird on my Mac laptop not a mobile phone. Are you saying that I need to go back to my Google account > Security settings and look for App settings and enter a new app for T-Bird and get a new PW just for T-Bird?

That's what I missed doing. I went back to my google account and went to the App section, entered a name and device for T-Bird to get a new PW. Entered that PW into T-Bird and it connected.

I generated and entered an app-specific password into the connect google talk dialog in Thunderbird (60.3.0 64-bit). still says not authorized. I have 2fa set in google. old help messages refer to the "turn on allow less secure apps" option which no longer exists.